ever lead in a way that's contrary to biblically revealed ethics?
No, of course not. The Holy Spirit couldn't possibly lead somebody to disobey the Holy Spirit's teaching. That would be God acting against himself. I would think it would be elementary and manifestly obvious to every Christian that God the Holy Spirit will not give you as an individual a leading to act in defiance of the written Word of God.
I speak so strongly about this precisely because I run into people all the time who tell me that God has given them an inclination or a private leading that excuses them from the moral obligations God has set forth. I've had people tell me that they prayed about committing adultery and that God the Holy Spirit gave them peace about it. How much lower can you go? That's not blasphemy against the Holy Spirit, but that certainly grieves the Holy Spirit. It also comes perilously close to blasphemy against the Holy Spirit to not only refuse to repent of sin but to attribute the motivation and the license for it to God himself. This is the propensity we have, to call good evil and evil good.
I've seen otherwise devout and earnest Christians talk in this manner. I've had biblical scholars look me straight in the eye and tell me that the Holy Spirit gave them permission to do something that God clearly prohibits in his Word. This is one of the reasons the Scriptures tell us to test the spirits to see if they are from God. How do we test a spirit? How do I know if I have the leading of the Holy Spirit? That can be a very whimsical and subjective type of thing. I do believe that God the Spirit inclines our hearts in certain directions and will help to lead us in the living of this life, but we have to be very careful lest we confuse the leading of the Spirit with indigestion or, what's worse, the leading of the anti-Spirit, the leading of the enemy himself, who would seek to lead us astray. Remember that Satan disguises himself as an angel of light.
If you believe that the Scriptures come through the inspiration of God the Holy Spirit and that he is the Spirit of truth and it is that truth that is embodied in the sacred Scripture, then the easiest way to test any private inclination or group leaning that you get from other people is with the written Word of God. I'm confident that there we have the leading of the Spirit. There the Spirit is inspired. The Spirit of truth has set forth for us in the propositions of Scripture what is pleasing to God and in keeping with his perfect will. I can't conceive of God the Spirit telling me to disobey what God has spoken.
~ Now - That's a Good Question! by R.C. Sproul